I could celebrate you could celebrate he could celebrate we could celebrate you could celebrate they could celebrate
V-ing form
I could be celebrating you could be celebrating he could be celebrating we could be celebrating you could be celebrating they could be celebrating
Perfect
I could have celebrated you could have celebrated he could have celebrated we could have celebrated you could have celebrated they could have celebrated
V-ing perfect
I could have been celebrating you could have been celebrating he could have been celebrating we could have been celebrating you could have been celebrating they could have been celebrating
Negation
Simple form
I could not celebrate you could not celebrate he could not celebrate we could not celebrate you could not celebrate they could not celebrate
V-ing form
I could not be celebrating you could not be celebrating he could not be celebrating we could not be celebrating you could not be celebrating they could not be celebrating
Perfect
I could not have celebrated you could not have celebrated he could not have celebrated we could not have celebrated you could not have celebrated they could not have celebrated
V-ing perfect
I could not have been celebrating you could not have been celebrating he could not have been celebrating we could not have been celebrating you could not have been celebrating they could not have been celebrating
Interrogative form
Simple form
could I celebrate? could you celebrate? could he celebrate? could we celebrate? could you celebrate? could they celebrate?
V-ing form
could I be celebrating? could you be celebrating? could he be celebrating? could we be celebrating? could you be celebrating? could they be celebrating?
Perfect
could I have celebrated? could you have celebrated? could he have celebrated? could we have celebrated? could you have celebrated? could they have celebrated?
V-ing perfect
could I have been celebrating? could you have been celebrating? could he have been celebrating? could we have been celebrating? could you have been celebrating? could they have been celebrating?
Interro-negative form
Simple form
could I not celebrate? could you not celebrate? could he not celebrate? could we not celebrate? could you not celebrate? could they not celebrate?
V-ing form
could I not be celebrating? could you not be celebrating? could he not be celebrating? could we not be celebrating? could you not be celebrating? could they not be celebrating?
Perfect
could I not have celebrated? could you not have celebrated? could he not have celebrated? could we not have celebrated? could you not have celebrated? could they not have celebrated?
V-ing perfect
could I not have been celebrating? could you not have been celebrating? could he not have been celebrating? could we not have been celebrating? could you not have been celebrating? could they not have been celebrating?